1. Field of the Invention
The current invention relates to a camera system for making video images of moving or still objects illuminated by pulsed gamma or neutron radiation.
2. Discussion of Prior Art
Solid state charge coupled device "CCD" cameras when used in a high energy gamma or, neutron radiation environment (whether pulsed or not) suffer from radiation induced artefacts. These artefacts are caused by scattered gamma or neutron radiation and are referred to by those skilled in the art as gamma induced background or neutron stars. These artefacts arise when the scattered gamma or neutron radiation passes through the camera structure to directly affect an imaging sensor within the camera. As a result an image produced by the sensor, lacks purity because of these radiation induced artefacts. In some circumstances the image is totally masked by the artefacts. Shielding the camera from the source of radiation in many instances is either impractical or ineffective.
The problem to which the current invention is addressed can be illustrated by referring to a paper in IEEE Transactions on Nuclear Science Vol 39 No Oct. 5, 1992. Experiments discussed in this paper demonstrate the capability to measure bursts of neutron fluences and gamma or X-ray fluxes directly with CCD cameras. In these experiments the neutron fluences or gamma fluxes form not only the incident beam but also give rise inevitably to scattered neutron fluences or scattered gamma beams that directly interfere with the television "TV" camera sensor during the same time window.
A conflict arises in that an image that is formed on a radiation to light converter or fluorescer by the incident beam has both intensity and spatially quantifiable information whereas the image formed on the TV camera sensor by the scattered beams have neither. Consequently, when both the image on the fluorescer and the TV sensor are combined in the TV sensor the result is a composite from both sources.